Synthesis and characterization of lanthanide [Ln(L)]{sub 2} complexes of N{sub 4}O{sub 3} amine phenol ligands with phenolate oxygen bridges: Evidence for very weak magnetic exchange between lanthanide ions
- Univ. of British Columbia (Canada); and others
The synthesis and characterization of three potentially heptadentate (N{sub 4}O{sub 3}) amine phenols and of a series of their mononuclear and dinuclear lanthanide complexes are reported. The heptadentate ligands are KBH{sub 4} reduction products of the Schiff bases derived from the condensation reactions of tris(2-aminoethyl)amine with 3 equiv of a salicylaldehyde compound. The reaction of an amine phenol with 1 equiv of a lanthanide (Ln) nitrate produces the mononuclear complex [Ln(H{sub 3}L)(NO{sub 3}{sub 3})]; homodinuclear complexes [Ln(l)]{sub 2} were obtained from the reaction of lanthanide salts with the respective ligand in the presence of a base (hydroxide or acetate). The X-ray structure of [Gd(L1)]{sub 2}{center_dot}2CHCl{sub 3} (H{sub 3}L1 = tris(((2-hydroxybenzyl)amino)ethyl)amine) has been determined; it is first structurally characterized example of an [Ln(L)]{sub 2} complex, a homodinuclear eight-coordinate lanthanide complex [Ln(L)]{sub 2} with heptadentate ligands only. The structure was solved by conventional heavy-atom methods and was refined by full-matrix least-squares procedures. The dinuclear complex [Gd(L1)]{sub 2} {center_dot}2CHCl{sub 3} has a distorted bicapped octahedral (or cubic) coordination geometry around each gadolinium atom which is coordinated by an N{sub 4}O{sub 4} donor set. The two gadolinium atoms are bridged by two phenolate O atoms, one from each heptadentate ligand. Room-temperature magnetic susceptibilities of some of the mononuclear and homodinuclear complexes give no indication of magnetic interaction between the two Ln{sup 3{minus}} ions and are discussed in relation to their structures. A variable-temperature (4.2-82 K) magnetic susceptibility study of the [Gd(L1)]{sub 2}{center_dot}2CHCl{sub 3} complex revealed a good fit of the data to two very weakly antiferromagnetically coupled S= 7/2 ions (g = 2.00, - J = 0.045 (1) cm{sup {minus}1}). 38 refs., 2 figs., 10 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 458096
- Journal Information:
- Journal of the American Chemical Society, Vol. 114, Issue 15; Other Information: PBD: 15 Jul 1992
- Country of Publication:
- United States
- Language:
- English
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